Technical Abstract:
An outlet works is a combination of structures and equipment required for the safe operation and control of water released from a reservoir to serve various purposes like regulating stream flow and water quality; releasing floodwater; and/or providing irrigation, municipal, or industrial water. Outlet works may include an intake structure, conduit, control house-gates, regulating gate or valve, gate chamber, and/or an energy dissipation structure. An energy dissipation structure slows the velocity and dissipates the energy of the flow released from an outlet works. A plunge basin is a deep pool energy dissipater into which a free jet of water can fall. The natural shape of a plunge basin is elliptical with a greater length parallel to the jet flow. Riprap and/or concrete are common materials used to line a plunge basin, but the plunge basin may be unlined to allow the scour to result from the hydraulic action of a free falling jet. This chapter discusses the types of plunge basins, jet trajectory of the discharge jet into a plunge basin, a description of the scour process for plunge basins, plunge basin design, and the use of slide gates with plunge basins.